Ambitious Climate Mitigation Research Articles

Guest Editorial: Special Issue on “Sustainable urban energy systems – Governance and citizen involvement”

Cities are responsible for over 75% of the total amount of global greenhouse gas emissions. They are also home to the majority of the Earth's population. Ambitious climate mitigation goals can only be realized by transforming fossil based urban energy systems into sustainable, low-carbon ones. This is a multidisciplinary challenge that goes way beyond the technological dimension. In the Special Issue to which this Guest Editorial contributes, a multi-disciplinary perspective is used, exploring governance, institutional, ethical and other aspects, pertaining to citizen involvement in sustainable urban energy systems. The main research questions are, “How can we address key challenges to the analysis and design of sustainable urban energy systems, as regards their governance and institutions, values, social acceptance, and citizen involvement?”, and “How can this contribute to shaping a multi-disciplinary academic research agenda?” Based on the main findings from the ten contributions to the Special Issue key challenges to sustainable urban energy system design, planning, and implementation are presented, including suggestions for future research.

Integrating Shared Socioeconomic Pathway-informed adaptation into temperature-related mortality projections under climate change

The extent to which populations will successfully adapt to continued warming temperatures will be a crucial factor in determining future health burdens. Previous health impact assessments of future temperature-related mortality burdens mostly disregard adaptation or make simplistic assumptions. We apply a novel evidence-based approach to model adaptation that takes into account the fact that adaptation potential is likely to vary at different temperatures. Temporal changes in age-specific mortality risk associated with low and high temperatures were characterised for Scotland between 1974 and 2018 using temperature-specific RR ratios to reflect past changes in adaptive capacity. Three scenarios of future adaption were constructed consistent with the SSPs. These adaptation projections were combined with climate and population projections to estimate the mortality burdens attributable to high (above the 90th percentile of the historical temperature distribution) and low (below the 10th percentile) temperatures up to 2080 under five RCP-SSP scenarios. A decomposition analysis was conducted to attribute the change in the mortality burden into adaptation, climate and population. In 1980–2000, the heat burden (21 deaths/year) was smaller than the colder burden (312 deaths/year). In the 2060–2080 period, the heat burden was projected to be the highest under RCP8.5-SSP5 (1285 deaths/year), and the cold burden was the highest under RCP4.5-SSP4 (320 deaths/year). The net burden was lowest under RCP2.6-SSP1 and highest under RCP8.5-SSP5. Improvements in adaptation was the largest factor reducing the cold burden under RCP2.6-SSP1 whilst temperature increase was the biggest factor contributing to the high heat burdens under RCP8.5-SSP5. Ambient heat will become a more important health determinant than cold in Scotland under all climate change and socio-economic scenarios. Adaptive capacity will not fully counter projected increases in heat deaths, underscoring the need for more ambitious climate mitigation measures for Scotland and elsewhere.

Climate targets, carbon dioxide removal, and the potential role of ocean alkalinity enhancement

Abstract. The Paris Agreement to limit global warming to well below 2 ∘C requires the ambitious reduction in greenhouse gas emissions and the balancing of remaining emissions through carbon sinks (i.e., the deployment of carbon dioxide removal or CDR). While ambitious climate mitigation scenarios until now primarily consider land-based CDR methods, there is growing concern about their potential to deliver sufficient CDR, and marine CDR options are receiving more and more interest. Based on idealized theoretical studies, ocean alkalinity enhancement (OAE) appears as a promising marine CDR method. However, the knowledge base is insufficient for a robust assessment of its practical feasibility, of its side effects, social and governance aspects, and monitoring and verification issues. A number of research efforts aims to improve this in a timely manner. We provide an overview on the current situation of developing OAE as a marine CDR method and describe the history that has led to the creation of the OAE research best practices guide.

Accountability implications for intermediaries in upscaling: Energy community rollouts in Portugal

With the increasing diffusion of solar energy, its conditioning by intermediaries merits attention. Depending on the accountability relations between stakeholders, intermediaries can influence the speed of diffusion. We examine these aspects in the intensifying solar rollout in Portugal, a country with high energy prices, relatively low wages, and ambitious climate mitigation plans. Competitive modular photovoltaic costs and enabling energy community legislation have recently prompted several intermediaries to participate in developing energy communities. We analyse the roles of four types of organisations as intermediaries: non-profit institutions, municipalities, new entrant companies with innovative business models and the renewables arm of the incumbent. Their activities influence market structuration and, thus, the nature of the solar PV rollout. Each intermediary legitimises its role through various practices. Whereas some leverage existing networks, others combine innovative business models with the facilitation of energy infrastructure to advance replicable prototypes. Based on three months of multi-sited fieldwork in 2022 featuring 36 interviews, we analyse the emergent roles of intermediaries. In concert with the scholarship on market creation and diffusion pathways, we advance understanding of diffusion in a financially constrained context.

COASTAL WAVE OVERTOPPING: NEW NOWCAST AND MONITORING TECHNOLOGIES

It is projected that global mean sea level could rise up to 1 m this century with a strong regional pattern. It is estimated that 20percent of England’s coastal defenses could fail under just half this rise. Ambitious climate mitigation and adaptation plans may protect 400,000 – 500,000 people, but flood and coastal erosion risks cannot be fully eliminated. Building coastal climate resilience requires accurate wave overtopping prediction tools and nowcast information to prepare for and respond to coastal hazards. In Dawlish, SW England, a new monitoring system to measure concurrent beach level and wave overtopping conditions over a 1-year period was installed. The system obtains in-situ measurements of the inland wave overtopping distribution across a public walkway and railway line, and issues near real-time overtopping data to the British Oceanographic Data Centre, making it accessible online within 15 minutes of detection. This public web service also ingests near-real time wave and water level data from existing national coastal monitoring networks, providing a full dataset to validate and calibrate an operational wave, water-level and overtopping forecast system. Using these data, the numerical forecasts have been refined by incorporating recent beach levels to reduce the uncertainty in the wave overtopping predictions due to seasonal variability in the beach level at the toe of the sea wall.

The environmental dark side of digitalisation: an urban perspective

As primary hubs of consumption in an urban world, cities generate an ever-growing demand for energy-intensive digital services. If city governments are to stay true to their ambitious climate mitigation goals, they must play a pivotal role in addressing digitalisation’s environmental impacts and carbon emissions.

A MODEL INTERCOMPARISON OF THE WELFARE EFFECTS OF REGIONAL COALITIONS FOR AMBITIOUS CLIMATE MITIGATION TARGETS

This paper presents the overall and distributional welfare effects of alternative multi-regional emissions trading coalitions relative to unilateral action. It focusses on meeting Paris Agreement pledges and more emissions reduction targets consistent with 2∘C and 1.5∘C temperature pathways in 2030. The results from seven computable general equilibrium (CGE) models are compared. Across all models, welfare gains are highest with a global market and increase with the stringency of targets. All regional coalitions also show overall welfare gains, although lower gains than the global market. The models show more variability in the gains by a participant. Depending on the model, participants may benefit more from some regional arrangements than from a global market or face modest losses compared to the domestic reductions alone, due to interactions between carbon targets and fossil fuel markets. The scenario with a joint China–European Union emissions trading system in all sectors is consistently favorable for participants and provides the highest economic gains per unit of emissions abated.

Tackling the Global Environmental Problem of Climate Change through COVID-19 Economic Recovery Stimulus Packages: Some Suggested Legal Strategies

The effects of the COVID-19 are both immediate and dreadful. But another profound emergency is the planet's unfolding environmental crisis of climate change. Climate change disruption is getting to the point of no return. We must act decisively to protect our planet from both the COVID-19 and the existential problem of climate interruption. We need to turn the COVID-19 economic recovery process into a real opportunity to do things right for the future. The economic and social devastation caused by climate disruption will be many times greater than the current COVID-19 pandemic. COVID-19 pandemic-which is resulting in significant economic and political shifts worldwide, should be the international community's unique window of opportunity in which recovery plans can be instrumental in creating a more sustainable and resilient future through ambitious climate mitigation, adaptation, and financing aimed at building back better. This article, which adopted the doctrinal research methodology, examines how the global environmental problem of climate change can be tackled through COVID-19 economic recovery stimulus packages. The paper finds that focusing COVID-19 economic recovery stimulus packages on greener economy, renewable energies, circular economy, and reforestation can help tackle the global environmental problem of climate change. Further, the paper finds that there is a need for legal frameworks that guarantee investments in the suggested strategic areas taking insights from the European Commission Green Deal policy framework. This paper recommends that national governments and international financial lending institutions should focus their COVID-19 economic recovery stimulus packages on investments that tackle the global environmental problem of climate change. Keywords: Global environmental problem, climate change, COVID-19, economic recovery, stimulus packages, legal strategies, European Commission Green Deal DOI: 10.7176/JLPG/123-06 Publication date: August 31 st 2022

Overcoming the disconnect between energy system and climate modeling

Energy system models underpin decisions by energy system planners and operators. Energy system modelling faces a transformation: accounting for changing meteorological conditions imposed by climate change. To enable that transformation, a community of practice in energy-climate modelling has started to form that aims to better integrate energy system models with weather and climate models. Here, we evaluate the disconnects between the energy system and climate modelling communities, then lay out a research agenda to bridge those disconnects. In the near-term, we propose interdisciplinary activities for expediting uptake of future climate data in energy system modelling. In the long-term, we propose a transdisciplinary approach to enable development of (1) energy-system-tailored climate datasets for historical and future meteorological conditions and (2) energy system models that can effectively leverage those datasets. This agenda increases the odds of meeting ambitious climate mitigation goals by systematically capturing and mitigating climate risk in energy sector decision making.

The justice pitfalls of a sustainable transport transition

This article examines the potential adverse effects of sustainable transport transitions on justice. It is important for policy debates to consider how pro-environment policies may adversely impact social justice. We apply a broad conception of justice as comprising redistribution, representation and recognition to the transport transition in Bergen, Norway, with ambitious climate mitigation policies to be met primarily by reshaping transport. Through primary data collection and critical literature review, we identify several potential injustice effects of green transport transitions. These particularly relate to the redistributive effects of selective allocation of benefits and to less tangible processes of representation and recognition.

Role of climate goals and clean-air policies on reducing future air pollution deaths in China: a modelling study

Over 3 million people die every year from diseases caused by exposure to outdoor PM2·5 air pollution, and more than a quarter of these premature deaths occur in China. In addition to clean-air policies that target pollution emissions, climate policies aimed at reducing fossil-fuel CO2 emissions (eg, to avoid 1·5°C of warming) might also greatly improve air quality and public health. However, no comprehensive accounting of public health outcomes has been done under different energy pathways and local clean-air management decisions in China. We aimed to develop an integrated method for quantifying the health co-benefits from different climate, energy, and clean-air policy scenarios and to assess the relationship between climate and clean-air policies and future health burdens in China, where an ageing population will further exacerbate the effects of air pollution. For this modelling study, we used a China-focused integrated assessment model and a dynamic emission projection model to project future Chinese air quality in scenarios spanning a range of global climate targets (1·5°C, 2°C, national determined contributions [NDC], unambitious, baseline, and 4·5°C) and national clean-air actions (termed 2015-pollution, current-pollution, and ambitious-pollution). We then evaluated the health effects of PM2·5 air pollution in the scenario matrix using the air quality model and the latest epidemiological concentration-response functions from the 2019 Global Burden of Diseases, Injuries, and Risk Factors Study. We found that, without ambitious climate mitigation (eg, under current NDC pledge), Chinese deaths related to PM2·5 air pollution might not always decrease-and might often grow-by 2050 compared with the base year of 2015, regardless of clean-air policies and air quality improvements. For example, in the scenario that tracks China's current NDC pledge and uses the best available pollution control technologies (the ambitious-pollution and NDC goals scenario), PM2·5-related deaths in China would decrease slightly by 2030 to 1·23 million per year (95% CI 0·95-1·51) from 1·25 million (1·04-1·46) in 2015, but would not decrease further by 2050 (1·21 million, 0·86-1·60) despite substantial and continuous improvements in population-weighted air quality (from 27·2 μg/m3 in 2030 to 16·0 μg/m3 in 2050). The contrary trends of improving air quality and increasing PM2·5-related deaths in many of our scenarios revealed the extent to which extra efforts are needed to compensate for the increasing age of China's population in the future. With the scenarios that included ambitious clean-air policies and met international climate goals to avoid 1·5°C and 2°C of warming (the ambitious-pollution-2°C goals scenario and the ambitious-pollution-1·5°C goals scenario), we observed substantial decreases in China's PM2·5-related deaths of 0·32-0·55 million deaths compared with NDC goals in 2050, and age-standardised death rates decreased by 10·2-14·2 deaths per 100 000 population per year. Our results show that ambitious climate policies (ie, limiting global average temperature rise to well below 2°C) and low-carbon energy transitions coupled with stringent clean-air policies are necessary to substantially reduce the human health effects from air pollution in China, regardless of socioeconomic assumptions. Our findings could help policy makers understand the crucial links between climate policy and public health. The National Natural Science Foundation of China.

Modelling ambitious climate mitigation pathways for Australia's built environment

• We model operational and embodied GHG emissions for Australia's built environment. • The scope includes residential and commercial buildings. • A high ambition scenario delivers a 94% reduction in emissions compared to BAU. • Includes renewables, electrification, efficiency and material replacement. • Novel pathways analysis highlights options for net zero and net negative emissions. Achieving net zero operational and embodied greenhouse gas (GHG) emissions in the built environment is recognised in Australia and globally as a key strategy to address climate change and achieve the United Nations Sustainable Development Goals (SDGs). However, gaps in knowledge remain regarding potential national pathways to achieve this outcome in Australia. This study further extends and applies a national-scale integrated macroeconomic simulation model to explore coherent pathways to net zero emissions in the built environment sector by 2050. The scope of the study includes residential and commercial buildings and both operational and embodied emissions. It applies scenario analysis incorporating different levels of climate ambition, including a shift to renewable energy, electrifying buildings, improving energy efficiency and replacing carbon-intensive materials. We find that a high ambition scenario (Scenario 2) delivers a 94% reduction in GHG emissions by 2050 when compared against business-as-usual, placing a net-zero target within reach. Improvements on Australia's SDGs performance are also attained. Through subsequent pathways analysis we find that achieving net zero or even net negative operational and embodied emissions is feasible with more ambitious action in key areas, including increasing the share of mass-timber buildings and reducing end-of-life losses in sequestered carbon.

Clean cooking access may stall under slow post-pandemic recovery and ambitious climate mitigation without explicit focus

Without additional support policies, clean cooking could become unaffordable for about 470 million people by 2030 if a post-pandemic recovery is slow, and about 200 million people by 2030 under ambitious climate mitigation action. Acceleration of clean cooking transitions by tapping into pandemic recovery and climate funds to target the poorest people and regions globally is urgently needed.

Access to clean cooking services in energy and emission scenarios after COVID-19

Slow progress in expanding clean cooking access is hindering progress on health, gender, equity, climate and air quality goals globally. Despite a rising population share with clean cooking access, the number of cooking poor remains stagnant. In this study we explored clean cooking access until 2050 under three reference scenarios, a COVID-19 recovery scenario and ambitious climate mitigation policy scenarios. Our analysis shows that universal access may not be achieved even in 2050. A protracted recession after the pandemic could leave an additional 470 million people unable to afford clean cooking services in 2030 relative to a reference scenario, with populations in sub-Saharan Africa and Asia the worst affected. Ambitious climate mitigation needs to be twinned with robust energy access policies to prevent an additional 200 million people being unable to transition to clean cooking in 2030. Our findings underline the need for immediate acceleration in efforts to make clean cooking accessible and affordable to all. Many socioeconomic growth and low-emission energy scenarios do not consider impacts on clean cooking access and have yet to account for the COVID pandemic. Pachauri et al. now examine how clean cooking access evolves under various scenarios post COVID and find the need for policy focused on increasing access more urgent.

Taking control to do more: how local governments and communities can enact ambitious climate mitigation policies

ABSTRACT While local governments have emerged as policy leaders on climate change, evidence indicates that many of the policies enacted do not significantly reduce greenhouse gas emissions. This study focuses on ambitious climate policymaking, examining the stakeholders involved and their concerns, including the role of local control. The study analyzes Community Choice Aggregation in California, an impactful climate policy that local governments have pursued throughout the state over the past decade. A qualitative-driven approach is used, including interviews with policymakers and stakeholders in five areas of the state that adopted the policy and two areas that voted against it. An interconnected effort of local elected officials and grassroots groups led the policymaking process, driven by concern about climate change and a desire for local control. Grassroots engagement can be critical in building support and coalitions for ambitious climate policies. Stakeholders and governments embraced local control to shape policies to match their priorities and achieve a variety of co-benefits.

Personal carbon allowances revisited

Here we discuss how personal carbon allowances (PCAs) could play a role in achieving ambitious climate mitigation targets. We argue that recent advances in AI for sustainable development, together with the need for a low-carbon recovery from the COVID-19 crisis, open a new window of opportunity for PCAs. Furthermore, we present design principles based on the Sustainable Development Goals for the future adoption of PCAs. We conclude that PCAs could be trialled in selected climate-conscious technologically advanced countries, mindful of potential issues around integration into the current policy mix, privacy concerns and distributional impacts.

Global scenarios of household access to modern energy services under climate mitigation policy

Emission reduction scenarios to meet climate change mitigation policy goals rarely explore the differential impact of alternative pathways on access to energy for different economic strata of society across countries. Here we show that even under optimistic socioeconomic growth scenarios, inequalities in use of modern energy in homes could persist. We find that, although access improves in high growth scenarios, over 10% of populations in sub-Saharan Africa and South Asia could lack access to energy services for thermal comfort, food preparation and conservation, and cleaning in 2050. Ambitious climate mitigation scenarios do not substantially alter household access to energy services in the Global South, and only affect gas consumption in high-income regions. Our work suggests that efforts to meet climate mitigation policy goals are not at odds with progress towards universal access to modern energy services in the Global South, however, directed policy will be needed to meet access goals.

Carbon price dynamics in ambitious climate mitigation scenarios: an analysis based on the IAMC 1.5 °C scenario explorer

We analyse global carbon price trajectories from integrated assessment studies of 2 °C and below-compatible emission pathways based on a new scenario ensemble that has been made publicly available together with other relevant data sets in the IAMC 1.5 °C Scenario Explorer. We complement and extent the findings of the initial study on carbon price variations in integrated assessment models of (Guivarch and Rogelji 2017 Carbon price variations in 2 °C scenarios explored, Carbon Pricing Leadership Coalition) by providing a broader and more robust empirical assessment based on a comprehensive statistical analysis. We discuss the prospects and challenges of in‐depth bivariate econometric analyses of key impact factors in data sets from integrated assessment models. We show that the amount of meta‐information reported for individual models differs significantly across all variables where a large part of all recorded scenario explorer variables can be attributed to only a small number of applied models. We analyse the trend patterns emerging from the analysed global carbon price trajectories based on a statistical trend identification procedure. About half of the analysed carbon price projections seem to be best characterised by long run exponential growth patterns in carbon prices. Moreover, we break down the explanatory contribution of individual components on global carbon prices by the Kaya identity, i.e. global GDP, primary energy intensity and emission intensity. We show that the price of carbon is lower in baseline scenarios with faster economic growth per capita, low‐energy consumption patterns and high potentials for low carbon technologies compared to fossil fuels. In contrast to previous findings, the observed carbon price developments are impacted much more strongly by scenario‐specific than by model‐specific influences. Next to the diagnostic indicators for models, further indicators for the categorization of scenarios describing key context and policy parameterisations applied in individual model runs should be developed and included in descriptions of integrated assessment studies.

Deep uncertainties in shoreline change projections: an extra-probabilistic approach applied to sandy beaches

Abstract. Global mean sea level rise and its acceleration are projected to aggravate coastal erosion over the 21st century, which constitutes a major challenge for coastal adaptation. Projections of shoreline retreat are highly uncertain, however, namely due to deeply uncertain mean sea level projections and the absence of consensus on a coastal impact model. An improved understanding and a better quantification of these sources of deep uncertainty are hence required to improve coastal risk management and inform adaptation decisions. In this work we present and apply a new extra-probabilistic framework to develop shoreline change projections of sandy coasts that allows consideration of intrinsic (or aleatory) and knowledge-based (or epistemic) uncertainties exhaustively and transparently. This framework builds upon an empirical shoreline change model to which we ascribe possibility functions to represent deeply uncertain variables. The model is applied to two local sites in Aquitaine (France) and Castellón (Spain). First, we validate the framework against historical shoreline observations and then develop shoreline change projections that account for possible (although unlikely) low-end and high-end mean sea level scenarios. Our high-end projections show for instance that shoreline retreats of up to 200 m in Aquitaine and 130 m in Castellón are plausible by 2100, while low-end projections revealed that 58 and 37 m modest shoreline retreats, respectively, are also plausible. Such extended intervals of possible future shoreline changes reflect an ambiguity in the probabilistic description of shoreline change projections, which could be substantially reduced by better constraining sea level rise (SLR) projections and improving coastal impact models. We found for instance that if mean sea level by 2100 does not exceed 1 m, the ambiguity can be reduced by more than 50 %. This could be achieved through an ambitious climate mitigation policy and improved knowledge on ice sheets.

Transition towards urban system integration and benchmarking of an urban area to accelerate mitigation towards net-zero targets

Strengthening capacity for cross-sectoral coordination has a crucial role in enabling ambitious climate mitigation. This research work integrates the Sustainable Development of Energy, Water and Environment Systems Index into a policy framework with three main components to compare possibilities for improving urban system performance. Tiers of integration are defined and compared with the index results for more transformative action. The levels range from unintegrated urban sectors and emerging integration, including those with urban land use and spatial planning, to advanced integration across the urban system. The case study is based on a municipality that is benchmarked to receive an index score of 27.783, placing the urban area in rank 79 among 120 other cities. The measures in the existing action plan are compared with opportunities that would support the municipality in reaching higher tiers of urban integration in the future. Policy learning from other urban areas to which the index is applied is foreseen to support collective action in addressing synergistic opportunities for mitigation. The results have implications on considering urban system integration in the transition to net-zero targets, missions for climate-neutral cities, and the realization of 100% renewable energy systems.